This invention relates to a low pressure fluorescent mercury vapor discharge lamp having a particular type of phosphor coating to emit skin tanning radiation when excited by the ultraviolet radiation generated from the mercury vapor discharge. More particularly, the present type lamp construction provides satisfactory skin tanning with a preselected amount of radiation in the approximate 280-320 nanometer ultraviolet region of the spectrum. The ultraviolet radiation in this region is referred to as UVB radiation and can produce reddening of the skin from excessive lamp exposure such as can occur from overexposure to natural sunlight. It is also known, as set forth in U.S. Pat. No. 4,499,403 to Leppelmeier et al, that lamps emitting ultraviolet radiation in the approximate wavelengh region 320-400 nanometers can produce skin tanning without skin reddening to any significant degree. However, the American Conference of Governmental Industrial Hygienists has established "threshold limit" values for UVB and UVA emission. Hence, it desirabe to design lamps having emission within certain narrowly prescribed limits and develop production processes which can reliably meet the designed criteria.